The present invention relates to a shift control for a motor vehicle automatic transmission, and more particularly to an adaptive correction of in appropriate shift in an automatic transmission.
U.S. patent application Ser. No. 07/301,352 filed on Jan. 25, 1989 or the corresponding European Patent Application No. 89 101 294.0 (publication No. 0326119) disclose a shift control for a motor vehicle automatic transmission. According to this known shift control, the switching timings of shift solenoids for a power-off 1-2 upshift are determined after comparing the gear ratio with gear ratio values derived from predetermined switching timing tables, or after comparing a time elapsed from the issuance of command for a power-off 1-2 upshift with time values derived from predetermined switching timing tables.
Since the data in the above-mentioned switching tables are fixed, an inappropriate shift operation occurs if the speed at which the engine decreases its speed deviates from the initially set value owing to aging of the engine.
An object of the present invention is to provide an adaptive correction of such inappropriate shift in an automatic transmission.